Food allergy and food intolerance – a quick guide

by | Nov 13, 2023 | gut health and digestion

Food allergy and food intolerance are becoming more common. Yet there is a lot of confusion about the difference between them. In fact, as a herbalist, I am often asked about food sensitivity. So, here is a quick guide.

Food sensitivity

Food sensitivity can refer to either an allergy or intolerance to food. Basically it just means that you have a reaction to certain foods that you eat.

Food allergy

This is an immune system reaction to foods you have eaten. And the reaction usually occurs quickly after eating the foodstuff.  Sometimes within seconds. The symptoms can be mild or severe, even life-threatening in some cases. The most severe form of reaction is the anaphylactic reaction.

An allergy can occur to any part of your diet. But it would most likely be to one of these foods: milk, eggs, nuts, peanuts, fruits, wheat, soya and fish or shellfish.

Food allergy symptoms include:

  • tingling or itching or swelling  in the mouth or throat
  • difficulty swallowing or wheezing
  • an itchy red rash
  • sneezing or itchy eyes
  • feeling dizzy or nauseous
  • abdominal pain or diarrhoea

An anaphylactic reaction might begin with the symptoms above but can become more serious. With increased breathing difficulty, a rapid heartbeat, sudden drop in blood pressure and unconsciousness.

Skin-prick tests or blood tests for specific IgE antibodies can diagnose an allergy.

People with a confirmed allergy are more susceptible to future reactions. They need to avoid their trigger foods completely. After an anaphylactic reaction, it is best to carry an EpiPen or similar. These allow someone to self-inject adrenaline in an emergency.

Food intolerance

The symptoms of intolerance are much more diverse and are not a medical emergency. They are also likely to happen much longer after eating. Sometimes hours or days later. Symptoms can be vague and may not be associated with the foodstuff that caused them. And, the person may even tolerate a small amount of the suspect item but if they eat a larger portion, they can develop symptoms.

The most common symptoms of intolerance are gut symptoms. Including bloating, diarrhoea, constipation, skin problems and joint pain. Others might include brain fog, lethargy, headaches or migraine, or generally feeling unwell.

Causes of food intolerance include not being able to digest a meal properly. Or a reaction to something contained within the meal.

People with suspected food intolerance should keep a diary of meals and ingredients eaten and symptoms. Elimination of suspected items and later adding them back can identify intolerances. This can be a long and painstaking process. So, many people opt for a food intolerance test to speed up the process.

Whilst, certain intolerances could mean that some items must be completely avoided. In other cases, it is possible that after a period of elimination, the food may be eaten again.
So, while some of the symptoms of allergy and intolerance may be similar, food allergy can be a medical emergency, whereas food intolerance is not.


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